Motor vehicle engine use a loop serpentine belt to transfer part of the engine output to a plurality of belt drive attachments. Each component includes an input drive shaft and a belt wheel connected to a far end of the input drive shaft. The belt wheel is used to drive the belt. The torque produced by the engine is transferred to the belt wheel through the belt. The belt wheel drives the drive shaft of the alternator to rotate, in order to produce the alternating current by driving a mover to cut magnetic loop.
Most of the motor vehicle engines drive the piston moving up-and-down through the combustion of fuel oil or gas. The combustion makes the crankshaft accelerate and the compression makes the crankshaft decelerate. So the belt drive attachment is repeatedly accelerated and decelerated. In the process, the belt wheel drives the whole gear system (including generator, water pump, air condition, idler, and etc.) and produces larger vibration. This causes some bad effects, such as the increase of the engine vibration, noise and fuel consumption, and the decrease of the component life and vehicle comfort. In order to solve the above problem, a unidirectional clutch decoupling device (overrunning alternator decoupler), used for reducing and eliminating the vibration of the engine gear train, is provided.
U.S. Pat. No. 5,139,463 discloses a serpentine drive with coil spring alternator connection. In U.S. Pat. No. 5,139,463, a plastic bracket is used to connect the friction spring and the torsion spring in series. Part of the belt wheel vibration is absorbed by the torsion spring through deformation. The disadvantage of the above includes: first, the processing technique is difficult when the friction springs and torsion springs are connected in series, the docking accuracy is difficult to guarantee; second, the inner surface of T wheel needs to be milled a spiral stairs to fix the torsional spring, which leads to a low efficiency and high cost.
Accordingly, a new unidirectional clutch decoupling device is needed.